Novel preparation method of bimetallic Ni-In alloy catalysts supported on amorphous alumina for the highly selective hydrogenation of furfural

Article abstract of DOI:10.1016/j.mcat.2017.11.004

A novel preparation method for bimetallic nickel-indium alloy catalysts supported on amorphous alumina (Ni-In(x)/AA; x = Ni/In molar ratio) catalysts has been developed and evaluated for the highly selective hydrogenation of biomass-derived furfural. Ni-In(x)/AA catalysts were obtained via the hydrothermal treatment of Raney nickel supported on aluminium hydroxide (R-Ni/AlOH) and an InCl₂·H₂O solution in an ethanol/H₂O mixture at 423 K for 2 h, followed by reduction with H₂ at 573–873 K for 1.5 h. The formation of Ni-In alloy phases such as Ni₃In₂, Ni₃In, Ni₂In, and NiIn in Ni-In(2.0)/AA was clearly observed after reduction with H₂ at 873 K for 1.5 h. Ni-In(2.0)/AA contained a Ni₂In alloy as the major phase, which exhibited the best catalytic performance for the selective hydrogenation of furfural into furfuryl alcohol and was stable for at least five consecutive reaction runs.

Full text of DOI:10.1016/j.mcat.2017.11.004

Molecular Catalysis 445 (2018) 52–60
Contents lists available at ScienceDirect
Molecular Catalysis
journal homepage: www.elsevier.com/locate/mcat
Research Paper
Novel preparation method of bimetallic Ni-In alloy catalysts
supported on amorphous alumina for the highly selective
hydrogenation of furfural
a,∗
a
a
a
Rodiansono , Maria Dewi Astuti , Dwi Rasy Mujiyanti , Uripto Trisno Santoso ,
b,∗
Shogo Shimazu
Department of Chemistry, Lambung Mangkurat University, Jl. A. Yani Km 36 Banjarbaru 70714, Indonesia
a
b
Graduate School of Engineering, Chiba University, 1-33 Yayoi, Inage, Chiba, 263-8522, Japan
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 11 July 2017
Received in revised form 31 October 2017
Accepted 2 November 2017
A novel preparation method for bimetallic nickel-indium alloy catalysts supported on amorphous alumina
(Ni-In(x)/AA; x = Ni/In molar ratio) catalysts has been developed and evaluated for the highly selective
hydrogenation of biomass-derived furfural. Ni-In(x)/AA catalysts were obtained via the hydrothermal
®
treatment of Raney nickel supported on aluminium hydroxide (R-Ni/AlOH) and an InCl2·H2O solution
in an ethanol/H2O mixture at 423 K for 2 h, followed by reduction with H2 at 573–873 K for 1.5 h. The
formation of Ni-In alloy phases such as Ni3In2, Ni3In, Ni2In, and NiIn in Ni-In(2.0)/AA was clearly observed
after reduction with H2 at 873 K for 1.5 h. Ni-In(2.0)/AA contained a Ni2In alloy as the major phase, which
exhibited the best catalytic performance for the selective hydrogenation of furfural into furfuryl alcohol
and was stable for at least five consecutive reaction runs.
Keywords:
Bimetallic Ni-In alloy catalyst
Selective hydrogenation
Biomass-derived furfural
Furfuryl alcohol
©
2017 Elsevier B.V. All rights reserved.
1
. Introduction
ously published studies, several bimetallic alloy transition metal
catalysts (e.g., Ni-Sn [11–13], Ni-Fe [14,15], Ni-In [16] Pd-Cu [17],
and Pt-Zn [18]) have shown superior performance for the selective
hydrogenation of F compared with their single metal counterpart.
Delbecq et al. have suggested that an increase in the charge den-
sity of Pt metals by the addition of hyperelectronic metals or the
formation of a metal alloy could enhance the affinity towards the
Biomass feedstock valorizations are currently being explored
by using heterogeneous catalysts to produce bio-based platform
chemicals, fuels, and various commodity products. Furfural (F) is
one of the most promising biorefinery platform molecules because
it can be transformed into a wide range of value-added derivative
molecules, which can be used as plasticizers, solvents, agrochem-
icals, monomers in the production of resins (e.g., furfuryl alcohol
C
O bond rather than towards the C C bond to form unsatu-
rated alcohols in the hydrogenation of ␣,␤-unsaturated aldehydes
[19,20]. Moreover, unlike tin alloyed with Pt, the utilization of Ni-Sn
alloy-based catalysts for the selective hydrogenation of unsatu-
rated carbonyl compounds has been rarely investigated to date
[21].
(FA) and tetrahydrofurfuryl alcohol (THFA)) and gasoline blends
(e.g., methyl furan (MF) or terminal diols (e.g., pentanediol (PD))
[1–3]. F could be produced effectively from C-5 sugars in hemicel-
lulosic biomasses, such as xylan, arabinose and C-6 sugars in form
of glucose or fructose via acidic hydrolysis [4–6].Autor name:
Interactions between metals in bimetallic catalysts can mod-
ify their surfaces, which can be beneficial for the conversion
and upgrading of highly complex biomass fractions[7–9]. Cop-
per chromite was the first industrial bimetallic catalyst for the
hydrogenation of F under harsh reaction conditions (473–573 K,
In our previous investigations, we have reported the synthesis
of both bulk and supported bimetallic Ni-Sn alloy catalysts from
two types nickel precursors: first, from nickel salt (e.g., NiCl2 or
NiCl ·4H O) produced from both bulk and supported Ni-Sn alloys
2
2
®
[11] and, second, from Raney nickel supported on aluminium
hydroxide (R-Ni/AlOH), which produced a nickel-tin alloy sup-
ported on aluminium hydroxide (Ni-Sn(x)/AlOH; x = Ni/Sn molar
ratio) [12,13]. The catalysts showed high activity and selectivity
during hydrogenation of F to FA [11–13], and the catalyst that con-
2
0–30 MPa) with maximum FA yields of ca. 70% [10]. In previ-
sisted of the Ni Sn2 alloy dispersed on TiO2 allowed a remarkable
reduction in the reaction temperature from 453 K to 383 K [11]. We
have also recently reported the catalytic performance of the Ni-
∗ Corresponding authors.
3
E-mail addresses: rodiansono@unlam.ac.id ( Rodiansono),
shimazu@faculty.chiba-u.jp (S. Shimazu).
http://dx.doi.org/10.1016/j.mcat.2017.11.004
2
468-8231/© 2017 Elsevier B.V. All rights reserved.

Rodiansono et al. / Molecular Catalysis 445 (2018) 52–60
53
Sn alloy during hydrogenation of biomass-derived levulinic acid in
water to ␥-valerolactone (GVL) [22,23]. Over bulk Ni-Sn alloy cat-
alysts, a relatively high reaction temperature (433 K, 4.0 MPa H2,
The H2 uptake was determined through irreversible H2
chemisorption. After the catalyst was heated at 393 K under vac-
uum for 30 min, it was then heated at 673 K under H2 for 30 min.
The catalysts were subsequently cooled to room temperature under
vacuum for 30 min. The H2 measurement was conducted at 273 K,
and the H2 uptake was calculated according to a method described
in the literature [26,27].
6
h) was applied to achieve both a high conversion and GVL yield
(
99%) [22]. Alternatively, a GVL yield of >99% was obtained over
Ni-Sn(x)/AlOH catalysts at a lower reaction temperature (393 K)
compared to the bulk catalysts [23]. We found that the selectivity
of Ni could be controlled precisely by changing the Ni/Sn ratio in a
Ni-Sn alloy or of the dispersion of the Ni-Sn alloy on an appropriate
support that might play a key role in chemoselectivity enhance-
ment.
Herein, we report our extended investigation on a facile and
novel preparation method for nanosized bimetallic nickel-indium
alloy catalysts supported on amorphous alumina (denoted Ni-
In(x)/AA; x is Ni/In molar ratio and AA is amorphous alumina).
Ni-In(x)/AA catalysts were synthesized via a very similar synthetic
procedure to Ni-Sn(x)/AlOH, which has been reported elsewhere
2.3. Catalyst characterization
Powder X-ray diffraction (XRD) measurements were recorded
on a Mac Science M18XHF instrument using monochromatic CuK␣
radiation (␭ = 0.15418 nm). The XRD equipment operated at 40 kV
◦
◦
−1
and 200 mA with a step width of 0.02 and a scan speed of 4 min
(␣1 = 0.154057 nm, ␣2 = 0.154433 nm). Inductively coupled plasma
(ICP) measurements were performed on an SPS 1800H plasma
spectrometer by Seiko Instruments Inc., Japan (Ni: 221.7162 nm
and Sn: 189.898 nm). The BET surface area (SBET) and pore volume
[
12]. The effects of the loading amount of In and thermal treatment
on the activity and selectivity of Ni-In(x)/AA catalysts during the
hydrogenation of furfural to furfuryl alcohol were studied system-
atically.
(V ) were measured using N2 physisorption at 77 K on a Belsorp
Max (BEL Japan). The samples were degassed at 473 K for 2 h to
p
remove physisorbed gases prior to the measurements. The amount
of nitrogen adsorbed onto the samples was used to calculate the
BET surface area via the BET equation. The pore volume was esti-
mated to be the liquid volume of nitrogen at a relative pressure
of approximately 0.995 according to the Barrett–Joyner–Halenda
2
. Experimental
2.1. Reagents
(BJH) approach based on desorption data [25]. SEM images of the
synthesized catalysts were taken on a JEOL JSM-610 microscope
after the samples were coated using a JEOL JTC-1600 autofine
coater. TEM images were recorded on a JEOL JEM1400 microscope.
Raman spectra were collected on a JASCO NRS-2100 laser-Raman
spectrophotometer with an Ar beam lamp at excitations of 488 nm
and 514.5 nm.
Raney Ni-Al alloy (50%wt Ni and 50%wt Al) was purchased from
Kanto Chemical Co., Inc.). NaOH, InCl ·4H O and SnCl ·2H O were
3
2
2
2
purchased from WAKO Pure Chemical Industries, Ltd., and GaCl ,
3
AgNO , NbCl5, and ZrCl4 were purchased from Sigma-Aldrich, Co.,
3
and used as received. Furfural, furfuryl alcohol, tetrahydrofur-
furyl alcohol, ethanol, and isopropanol were purchased from Tokyo
Chemical Industries (TCI) Ltd. and purified using standard proce-
dures prior to use.
2.4. Typical procedure for the selective hydrogenation of furfural
The catalyst (50 mg), furfural (1.1 mmol), and isopropanol (3 mL)
2.2. Catalyst synthesis
as the solvent were placed into a glass reaction tube, which fit inside
a stainless steel reactor. After H2 was introduced into the reactor
at an initial H2 pressure of 3.0 MPa at room temperature, the tem-
perature of the reactor was increased to 383–453 K. After 75 min,
the conversion of furfural (F) and the yields of furfuryl alcohol (FA)
and tetrahydrofurfuryl alcohol (THFA) were determined using GC
analysis. The used Ni-In(2.0)/AA 773 K/H2 catalyst was easily sep-
arated using either simple centrifugation (4000 rpm for 10 min)
or filtration, then finally dried overnight under vacuum at room
temperature prior to re-usability testing.
2
.2.1. Synthesis of R-Ni/AlOH
A typical procedure for the synthesis of the Raney nickel sup-
ported on aluminium hydroxide catalyst (denoted as R-Ni/AlOH) is
described as follows [12,24]: Raney Ni-Al alloy powder (2.0 g) was
slowly added to a dilute aqueous solution of NaOH (0.31 M, 16 mL)
at room temperature. The temperature was raised to 363 K, and
4
3
reactor for hydrothermal treatment at 423 K for 2 h. The resulting
precipitate was filtered, washed with distilled water until the fil-
trate was neutralized and then stored in water. Finally, the catalyst
was dried under vacuum prior to use.
mL of3.1 MNaOHsolutionwassubsequentlyaddedandstirredfor
0 min. The mixture was then placed into a sealed Teflon autoclave
2.5. Product analysis
GC analysis of the reactant (F) and products (FA and THFA)
was performed on a Shimadzu GC-8A with a flame ionization
detector equipped with a silicone OV-101 packed column (length
2
.2.2. Synthesis of Ni-In/AlOH
A typical procedure for the synthesis of the nickel-indium alloy
(m) = 3.0; inner diameter (mm) = 2.0; methylsilicone from Sigma-
supported on aluminium hydroxide (denoted as Ni-In(2.0)/AlOH,
.0 is Ni/In molar ratio) consisted of first mixing R-Ni/AlOH at
Aldrich Co. Ltd.). Gas chromatography-mass spectrometry (GC–MS)
was performed on a Shimadzu GC–17 B equipped with a ther-
2
room temperature in an ethanol/H O solution (∼25 mL) that con-
2
1
mal conductivity detector and an RT-␤DEXsm capillary column. H
tained 4.5 mmol InCl ·4H O and then stirring for 2 h. The mixture
3
2
13
and C NMR spectra were obtained on a JNM-AL400 spectrome-
ter at 400 MHz; the samples for NMR analysis were dissolved in
chloroform-d1 with TMS as the internal standard. The products
were confirmed by a comparison of their GC retention time, mass,
was placed into a sealed Teflon autoclave reactor for hydrothermal
treatment at 423 K for 2 h. The resulting precipitate was filtered,
washed with distilled water and ethanol, and dried under vacuum
overnight. The Ni-In(x)/AlOH samples were reduced by hydrogen
1
13
H and C NMR spectra with those of authentic samples.
(
H ) at 673 K for 1.5 h, which produced Ni-In(x)/AA, where AA is
2
The conversion of furfural, yield and selectivity of the products
were calculated according to the following equations:
amorphous alumina. The Ni-In(2.0)/AlOH sample was reduced by
hydrogen (H ) at 573–873 K for 1.5 h in order to investigate the
2
effect of temperature reduction on the formation of the Ni-In alloy
in Ni-In(2.0)/AA.
introduced mol reactant(F0) − remained mol reactan(Ft )
Conversion :
x100%
introduced mol reactant(F0)

5
4
Rodiansono et al. / Molecular Catalysis 445 (2018) 52–60
mol product
Yeild :
x100%
consumed mol reactant (ꢀF)
molproduct
Selectivity :
x100%
totalmolproducts
where F0 is the introduced mol reactant (furfural, F), Ft is the
remaining mol reactant, and ꢁF is the consumed mol reactant
(
introduced mol reactant- remained mol reactant), which are all
obtained from GC analysis using an internal standard technique.
3
. Results and discussion
3.1. Catalyst characterization
A series of bimetallic alloys (Ni-In(x)/AA, x = Ni/In molar ratio)
prepared via hydrothermal treatment of a mixture of Raney®
nickel supported on aluminium hydroxide (R-Ni/AlOH) [12,24] and
InCl ·H O solution in ethanol/H O at 423 K for 2 h, produced the
2
2
2
as-prepared Ni-In(x)/AlOH. After reduction of the as-prepared Ni-
In(x)/AlOH with H2 treatment at 573–873 K for 1.5 h, Ni-In(x)/AA,
x = Ni/In molar ratio and AA = amorphous alumina were produced.
The physicochemical properties of the synthesized Ni-In(x)/AA cat-
alysts are summarized in Table 1.
Based on the ICP-AES results, the loading amounts of In were
−
1
1
.4, 2.3, 4.5, 6.2, and 9.4 mmol g , which was reflected by the Ni/In
Fig. 1. XRD patterns of (a) R-Ni/AlOH and the as-prepared Ni-In(x)/AlOH (x = Ni/In
molar ratio) at different Ni/In molar ratios of (b) 5.1, (c) 3.1, (d) 2.0, (e) 1.1, and (f)
molar ratios of 5.1, 3.1, 2.0, 1.1, and 0.8, respectively. The results
also indicate that SBET increased gradually, while the H2 uptake
decreased with an increase in the loading amount of In. The SBET
values of the Ni-In(x)/AA samples were higher than those of the as-
prepared samples (Ni-In(x)/AlOH) because of thermal treatment or
the formation of amorphous alumina. In the Ni-In(2.0)/AA sample,
0.8. (᭹) bayerite; (⊗) gibbsite; (#) In(OH)3; (ꢀ) Ni(0); (*) Ni2In3.
−
1
To confirm the formation of the bimetallic Ni-In alloy, the as-
the H2 uptake was 75 ␮mol g (entry 4), which is comparable to
the previous results of the H2 uptake of Ni-Sn(1.4)/AlOH [12]. An
increase in the loading amount of In reduced the surface activity of
Ni, as also indicated by the H2 uptake in samples with Ni/In ratios
of 1.1-0.8 (entries 5–7) and bulk Ni-In(2.0) (entry 8).
prepared Ni-In(x)/AlOH samples were reduced with H2 at 673 K for
.5 h and resulted in the bimetallic Ni-In alloy supported on amor-
1
phous alumina (denoted as Ni-In(x)/AA) and the XRD patterns are
shown in Fig. 2.
The results indicate that controlled thermal treatment under H2
transformed the remaining aluminium hydroxides (both bayerite
The average crystallite sizes of the Ni(111) species or bimetal-
lic Ni-In before and after H2 treatment were calculated by using
the Scherer equation using the diffraction peak at 2␪ = 44.4 and
the results are also summarized in Table 1. The findings indicate
that the average crystallite sizes of Ni(111) or bimetallic Ni-In are
largerthanthatoftheas-preparedsampledueto thermaltreatment
under hydrogen atmosphere. Compared with the bulk Ni-In(2.0)
catalyst with average crystallite sizes of bimetallic Ni-In of 39.8 nm
◦
and gibbsite phases) into amorphous alumina, which were not
◦
detectable using XRD analysis. The diffraction peak at 2␪ = 44.4
that is recognized as an identical peak of the Ni(111) species became
broadened and overlapped with the bimetallic Ni-In alloy phases
with an increase in the loading amount of In (Fig. 2a–e). A shoulder
◦
peak at 2␪ = 43.2 was also observed for a Ni/In ratio of 0.8 (where
the amount of Ni »In) that can be attributed to the formation of
(
entry 8), the crystallite sizes in Ni-In(x)/AA catalysts are much
the bimetallic Ni In species (#JCPDS-21-404) (Fig. 2e). Additionally,
smaller. The crystallite sizes of Ni or the Ni-In alloy in Ni-In(x)/AA
are also consistent with the H2 uptake. These results suggest that
the dispersion of active metal on amorphous alumina may influence
the catalytic activity.
The XRD patterns of R-Ni/AlOH and the as-prepared Ni-
In(x)/AlOH with different Ni/In molar ratios are shown in Fig. 1.
R-Ni/AlOH showed sharp diffraction peaks at 2␪ = 44.3 , 51.6 ,
and 76.3 , which correspond to the Ni(111), Ni(200), and Ni(220)
species, respectively (Fig. 1a). Sharp diffraction peaks were also
3
the broadened peak of the Ni(111) species both in the as-prepared
and H -treated samples suggest the formation of a bimetallic Ni-In
2
alloy that might have selectively occurred on the surface of Ni(111)
rather than on the surface of Ni(200) or Ni(220) [29–31].
The low-frequency Raman spectrum of the as-prepared Ni-
In(2.0)/AlOH resembles Ni-Sn(1.4)/AlOH, as has been previously
reported [23]. It is found that the low-frequency Raman spectrum
◦
◦
◦
−
1
showed a 530 cm band, which can be attributed to the ␥(OH)
−
1
◦
◦
◦
◦
vibrational mode and Al-O-Al deformation, whereas the 315 cm
observed at 2␪ = 18.3 , 27.8 , and 40.5 , which represent bayerite,
◦
◦
◦
◦
◦
◦
band is ascribed to Al-O-Al stretching vibrations of gibbsite or
bayerite (Fig. 3). Alternatively, the bands of Al-O-Al deformation
and at 2␪ = 18.7 , 20.4 , 36.7 , 37.8 , 53.2 , 63.9 , and 70.7 ,
which correspond to gibbsite (Fig. 1a–f). In contrast, the XRD
patterns of the as-prepared Ni-In(x)/AlOH exhibited broadened
and Al-O-Al stretching vibrations disappeared after H treatment at
2
◦
673 K for 1.5 h (Fig. 3b) due to the formation of amorphous alumina
peaks at 2␪ = 44.4 due to the formation of bimetallic Ni-In, i.e.,
[
32–34], which had been not detected by XRD [12,13]. Scanning
Ni In and Ni In (Fig. 1b–f). The formation of bimetallic Ni In
2
3
2
2
3
◦
#JCPDS-36-1147) at 2␪ = 31.9 and indium oxides such as In O
2
electron microscopy (SEM) images, EDS spectra and TEM images of
both Ni-In(3.1)/AA and Ni-In(2.0)/AA are shown in Figs. S1, S2, and
S3 (see ESI), respectively.
(
(
3
◦
◦
◦
◦
#JCPDS-06-416) at 2␪ = 22.4 , 39.4 , 51.0 , and 57.6 were also
observed (Figure d–f) [24,28].

Rodiansono et al. / Molecular Catalysis 445 (2018) 52–60
55
Table 1
Physicochemical properties of the synthesized bimetallic Ni-In alloy catalysts supported on amorphous alumina (Ni-In(x)/AA, x = Ni/In molar ratio).
Catalystsa
Nia
mmol 1
Ina
H2 uptakeb/
SBETc
/
D /nm
d
Entry
−
−1
−1
m2
−1
g
(
)
(mmol
)
␮mol g
1
2
3
4
5
6
7
Raney Ni
R-Ni/AlOH
4.0
3.5
7.1
7.2
8.8
7.0
7.2
4.1
0
0
121
104
84
71
75
76
48
29
70
150
8.6
9.0
Ni-In(5.1)/AA
Ni-In(3.1)AA
Ni-In(2.0)/AA
Ni-In(1.1)/AA
Ni-In(0.8)/AA
Bulk Ni-In(2.0)
1.4
2.3
4.5
6.2
9.4
2.0
128(101)
120(90)
154(98)
161(75)
157(72)
43
8.0(5.2)
7.0(3.8)
3.8(2.9)
6.6(3.9)
5.2(3.4)
39.8
e
8
a
Values between parentheses are the Ni/In molar ratios determined by ICP-AES.
Based upon the total H2 uptake at 273 K (after corrections for physical and chemical adsorption).
Specific surface area of BET (SBET) of samples after H2 treatment at 673 K for 1.5 h, determined by N2 adsorption at 77 K; values between parentheses are the SBET values
b
c
of the as-prepared samples.
d
Average Ni(111) or Ni-In crystallite sizes were calculated according to the Scherer equation; values between parentheses are the crystallite sizes of Ni(111) or Ni-In of
the as-prepared catalysts.
e
Bulk Ni-In(2.0) catalysts were synthesized via the hydrothermal treatment of a mixture of NiCl2 and InCl3·4H2O solutions at 423 K for 24 h, followed by H2 treatment at
6
73 K for 1.5 h.
3
.2. Catalytic reactions: furfural hydrogenation
decreased without the presence of H2 (entry 6). The R-Ni-In/SiO
2
−
1
catalyst (loading amount of In, 2.7 mmolg ) produced a 43% con-
version and a 39% yield of FA (entry 9). Moreover, the In/AlOH,
In O , and InCl ·4H O catalysts (entries 10–12) and the absence of
3.2.1. Selection of the second metals
At the first stage, the catalytic performances of various tran-
2
3
3
2
sition metal modified-R-Ni/AlOH, such as Sn, In, Ga, Ag, Nb, and
Zr, were first evaluated by the selective hydrogenation of the
typical unsaturated aldehyde furfural (F) to furfuryl alcohol (FA),
which is a promising chemical intermediate for the synthesis of
biosourced products widely used in the polymer industry. Con-
ventional Raney nickel (Raney Ni) and Raney nickel supported on
aluminium hydroxide (R-Ni/AlOH) catalysts were also synthesized
and evaluated using the same reaction conditions as catalyst refer-
ences. The detailed information for these catalysts is summarized
in Table S1 in the ESI. The XRD patterns of the as-prepared R-Ni-
M/AlOH are shown in Fig. S4 in the ESI. The results of the catalytic
hydrogenation of F are summarized in Table 2, and the reaction
pathways are shown in Scheme 1.
Conventional Raney Ni exhibited a 99.6% conversion of F and FA
and THFA yields of 48% and 51%, respectively (entry 1). As expected,
by using the R-Ni/AlOH catalyst, F converted completely to produce
a 99% yield of THFA (entry 2). Interestingly, the addition of Sn or In
shifted the product selectivity to FA with yields of 91% and 40%,
respectively (entries 3 and 4). In tin-alloyed Ni-based (Ni-Sn) cat-
alysts, the catalytic performances have been reported previously
a catalyst (entry 13) did not produce hydrogenated products of F
under the same conditions. In addition, screening tests using sol-
vents (e.g., methanol, ethanol, toluene, 1-propanol, and H O) other
2
than isopropanol (iso-PrOH) were also performed, and the results
were inferior to the results with iso-PrOH, as reported previously
[35].
The H treatment of as-prepared Ni-In(x)/AlOH at 673 K for 1.5 h
2
resulted in Ni-In(x)/AA catalysts (the XRD patterns are shown in
Fig. 2). The catalysts were evaluated for the catalytic hydrogenation
of biomass-derived furfural to furfuryl alcohol, and the results are
summarized in Table 4. Interestingly, over H -treated Ni-In(x)/AA
2
catalysts, the high conversion of F was achieved and produced a
high yield of FA (entries 1–6). In Ni-In(2.0)/AA, F was converted
completely into almost a 100% yield of FA. The high yield of FA
without the formation of THFA, even though the reaction time was
prolonged to 360 min (entry 4), obviously indicated the impor-
tant role of In in the Ni-In alloy catalyst system. Additionally, over
the indium-modified Raney Ni supported on silica (RNi-In/SiO2
673 K/H ) catalyst, the conversion of F was 96% with yield of FA
2
that was much lower than that of Ni-In(2.0)/AA under the same
reaction conditions (entry 7). The XRD patterns of this catalyst are
shown in Fig. S5 in the ESI, and the physicochemical properties are
summarized in Table S1 in the ESI. Moreover, by using the bulk Ni-
In(2.0) catalyst (XRD patterns are shown in Fig. S6 in the ESI), the
conversion of F was only 42% under the same reaction conditions
(entry 8).
[
11–13,22,23]. Alternatively, the presence of Ga, Ag, and Nb signifi-
cantly reduced the activity of R-Ni/AlOH (entries 5, 6, and 7), while
Zr did not affect the activity or selectivity of the former catalyst
(
entry 8). Therefore, in the present report, we focused on catalytic
performance studies of indium-alloyed Ni catalysts on F hydro-
genation including the effect of loading amount, H treatment, time
2
profiles, and catalyst reusability.
3
.2.2. Effect of In loading amount
The results for the selective hydrogenation of F using the
3.2.3. Effect of thermal treatment on Ni-In(2.0)/AlOH catalysts
Among the synthesized Ni-In(x)/AA catalysts, Ni-In(2.0)/AA
demonstrated a very high activity and selectivity towards the
desired product of FA. Therefore, we investigated the effect of tem-
perature during hydrogen treatment on Ni-In(2.0)/AA at 573–873 K
for 1.5 h, and the XRD patterns are shown in Fig. 4. After H2 treat-
ment at 573 K, the diffraction peaks of the aluminium hydroxides
(e.g., bayerite and gibbsite) totally disappeared, and the broadened
as-prepared supported bimetallic Ni-In(x)/AlOH catalysts are sum-
marized in Table 3.
It can be observed that after introducing 1.4 mmol InCl ·4H O
3
2
to R-Ni/AlOH, the conversion of F drastically decreased to 47% and
yielded 40% FA (entry 1). By increasing the loading amount of In
−1
to 9.4 mmolg , the FA yield was almost constant (entries 7 and 8,
1% and 39%, respectively). The prolonged reaction time of 180 min
◦
5
peaks at 2␪ = 42-44.5 were hardly distinguished due to the overlap
over Ni-In(2.0)/AlOH produced a marked increase in the FA yield
from 55% to 92% (entries 3 and 4, respectively). In contrast, the
yield of tetrahydrofurfuryl alcohol (THFA) decreased to 4% (entry
of the bimetallic alloy Ni-In phases and Ni metal diffraction peaks.
◦
Peak formation of NiIn (PDF#07-0178) at 2␪ = 30.2 and the remain-
◦
◦
ing In O3 at 2␪ = 22.3 and 31.9 was clearly observed (Fig. 4a-b).
2
4
). The FA yield decreased when an initial H2 pressure of 2.0 MPa
The increase in temperature from 673 K to 873 K transformed the
NiIn alloy species to Ni In (PDF #65-3486), Ni In (PDF#65-3522)
was applied (entry 5, 40%). The F conversion and FA yield drastically
2
3

5
6
Rodiansono et al. / Molecular Catalysis 445 (2018) 52–60
Table 2
Results of the catalytic hydrogenation of biomass-derived furfural over the various as-prepared bimetallic Ni-M/AlOH catalysts (M = Sn, In, Ga, Ag, Nb, and Zr).
a
−1
b
b
Entry
Catalyst
M /mmolg
Conversion /%
Yield /%
FA
THFA
1
2
3
4
5
6
7
8
Raney Ni
–
–
99
48
1
91
40
0
7
6
0
51
99
3
7
0
16
17
96
R-Ni/AlOH
Ni-Sn/AlOH
Ni-In/AlOH
Ni-Ga/AlOH
Ni-Ag/AlOH
Ni-Nb/AlOH
Ni-Zr/AlOH
> 99
95.0
47.0
12.8
44.9
47.3
> 99
1.0
1.4
1.1
1.2
1.2
1.1
Reaction conditions: catalyst (50 mg), F (1.1 mmol), iso-PrOH (3 mL), H2 (3.0 MPa), 453 K, 75 min.
a
Loading amount of In was determined by ICP-AES.
Scheme 1. Reaction pathways of furfural hydrogenation over bimetallic Ni-In catalysts.
Table 3
Results of the catalytic hydrogenation of biomass-derived furfural over as prepared bimetallic Ni-In(x)/AlOH catalysts with various loading amounts of indium (In).
Catalysta
b
−1
Conversion /%
c
c
Entry
In /mmolg
Yield /%
FA
THFA
1
2
3
Ni-In(5.1)/AlOH
Ni-In(3.1)/AlOH
Ni-In(2.0)/AlOH
Ni-In(2.0)/AlOH
Ni-In(2.0)/AlOH
Ni-In(2.0)/AlOH
Ni-In(1.1)/AlOH
Ni-In(0.8)/AlOH
R-Ni-In/SiO2
1.4
2.3
4.5
4.5
4.5
4.5
6.2
9.4
2.7
4.5
–
47
53
61
96
45
17
59
42
43
28
28
52
15
40
47
55
92
40
5
51
39
39
0
7
6
6
4
5
2
8
3
4
0
3
1
0
d
4
5
6
e
f
7
8
9
g
1
1
1
1
0
1
2
3
In/AlOH
In2O3
6
3
0
InCl3·4H2O
–
–
Neat (no catalyst)
a
b
c
d
e
f
Values between parentheses are the Ni/In molar ratio. Reaction conditions: catalyst (50 mg), F (1.1 mmol), iso-PrOH (3 mL), H2 (3.0 MPa), 453 K, 75 min.
Loading amount of In was determined by ICP-AES.
Conversion and yield were determined by GC analysis using an internal standard.
Reaction time was 180 min.
Initial pressure of H2 was 2.0 MPa.
Reaction occurred in the absence of H2.
g
Precursor of nickel was Raney Ni and supported on SiO2.
and Ni In (PDF # 65–3486) alloy phases (Fig. 4c–e), and the peaks
became intensified at a temperature of 873 K (Fig. 4e).
The results of the catalytic hydrogenation of F to FA and THFA
over Ni-In(2.0)/AA treated with H2 at different temperature treat-
ments are summarized in Table 5. For Ni-In(2.0)/AA catalysts at
uct was obtained over those catalysts (5% and 1% yield of THFA,
respectively). The best catalytic performance was achieved over
Ni-In(2.0)/AA 773 K (entry 3) and Ni-In(2.0)/AA 873 K (entry 4). We
also intentionally carried out the hydrogenation reaction of FA as
substrate over Ni-In(2.0)/AA 773 K under the same reaction condi-
tions, and only 5.2% of FA was converted into THFA with a yield of
2
3
5
73 K (entry 1) and 673 K (entry 2), a small amount of THFA prod-

Rodiansono et al. / Molecular Catalysis 445 (2018) 52–60
57
Table 4
Results of the catalytic hydrogenation of biomass-derived furfural over bimetallic Ni-In(x)/AA catalysts after H2 treatment at 673 K for 1.5 h.
Catalysta
In /mmol
b
g−1
Conversion /%
c
Yield /%
c
Entry
FA
THFA
1
2
3
Ni-In(5.1)/AA
Ni-In(3.1)/AA
Ni-In(2.0)/AA
Ni-In(2.0)/AA
Ni-In(1.1)/AA
Ni-In(0.8)/AA
RNi-In/SiO2
1.4
2.3
4.5
4.5
6.2
9.4
2.7
2.0
98
97
>99
>99
99
97
96
42
94
95
100
99
96
93
87
42
4
2
0
1
3
4
9
0
d
4
5
6
7
e
8
Bulk Ni-In(2.0)
a
Values between parentheses are the Ni/In molar ratio. Reaction conditions: catalyst (50 mg), F (1.1 mmol), iso-PrOH (3 mL), H2 (3.0 MPa), 453 K, 75 min.
Loading amount of In was determined by ICP-AES.
Conversion and yield were determined by GC analysis using an internal standard.
Reaction time was 360 min.
b
c
d
e
Bulk Ni-In(2.0) catalyst was synthesized via hydrothermal treatment of NiCl2 and InCl3·4H2O in an ethanol/H2O mixture at 423 K for 2 h, subsequently followed by
reduction with H2 at 673 K for 1.5 h. The XRD patterns of the as-prepared and H2-treated bulk Ni-In(2.0) samples are shown in Fig. S6 in the ESI.
Table 5
Results of furfural hydrogenation over various Ni-In(2.0)/AA catalysts after H2 treatment at various temperature of 573–873 K for 1.5 h.
a
a
Entry
Catalyst
Temp. H2 treatment/K
Conversion /%
Yield /%
FA
THFA
1
2
3
4
Ni-In(2.0)/AA
Ni-In(2.0)/AA
Ni-In(2.0)/AA
Ni-In(2.0)/AA
Ni-In(2.0)/AA
573
673
773
873
773
>99
>99
>99
>99
5
95.0
99.0
99.9
99.9
–
5.0
1.0
0
0
5.0
b
5
Reaction conditions: catalyst (50 mg), furfural (1.1 mmol), iso-PrOH (3 mL), H2 3.0 MPa, 453 K, 75 min.
a
Conversion and yield were determined by GC analysis using an internal standard.
Furfuryl alcohol (FA) was the substrate, and reaction time was 180 min.
b
Table 6
5
5
%, even after the reaction time was prolonged to 180 min (entry
). These results suggest that the addition of indium to R-Ni/AlOH
Results of the re-usability tests for the Ni-In(2.0)/AA 773 K/H2 catalyst in the selec-
tive hydrogenation of furfural.
to form the bimetallic Ni-In alloy retards the C C hydrogenation
activity of nickel, and as a result, further hydrogenation of the C
Runa
1
2
3
4
5
C
furan ring in F did not proceed in the presence of the Ni-In(2.0)/AA
catalyst.
Conversion (%)
Selectivity (%)
>99
100
95
99
93
99
91
99
91
99
b
Reaction conditions: F, 1.1 mmol (F/Ni ratio = 15); iso-PrOH (3 mL); H2, 3.0 MPa, 453 K,
7
5 min.
3.2.4. Effect of temperature
a
The recovered catalyst was reused without any further treatment.
Selectivity to FA was determined by GC analysis using an internal standard
The effect of temperature on the catalytic hydrogenation of F
b
to FA was evaluated over both Ni-In(2.0)/AA 773 K/H2 and bulk Ni-
In(2.0) catalysts, and the results are shown in Fig. 5. Differences
in the activity of each catalyst were clearly observed. On the bulk
Ni-In(2.0) catalyst, the conversion of F gradually increased as tem-
perature increased, and the highest conversion of F (∼76%) was
achieved at 453 K at the current reaction conditions. In contrast, F
was converted completely at 443 K over the Ni-In(2.0)/AA 773 K/H2
catalyst. These results are very similar to the bimetallic Ni-Sn alloy
catalyst system, in which bulk Ni-Sn catalysts have much lower
activity and reactivity during F hydrogenation compared with the
supported Ni-Sn catalysts, as reported previously [11].
technique.
increased to achieve a 75% yield, even after 180 min. Therefore, a
similar explanation can be applied to the current results as follows.
The induction periods could be associated with the slow formation
of oxidic tin (Sn ) from metallic tin (Sn ), as reported by Sordelli
et al. (Rh-Sn) [36] and Margitfalvi et al. (Pt-Sn) [37]. Since the crys-
tallite size or dispersion of Ni-In alloy could affect the length of
the induction period, the induction period of Ni-In(2.0)/AA dimin-
ished, and a 100% F conversion (>99% FA yield) was achieved after
n+
0
7
5 min. The excellent catalytic performance of Ni-In(2.0)/AA pro-
duces a promising candidate suitable for the large-scale production
of FA from the selective hydrogenation of furfural (F).
3
.2.5. Effect of initial H2 pressure
The effect of the initial H pressure on F conversion and product
2
selectivity was evaluated over the Ni-In(2.0)/AA 773 K/H2 catalyst,
and the results are shown in Fig. 6. F conversion and FA selectivity
gradually increased as the initial H2 pressure increased, whereas
the THFA selectivity decreased smoothly to almost 0% between 2.5
and 3.0 MPa and then gradually increased between 3.5–4.0 MPa.
3.2.7. Re-usability test
A re-usability test was performed on the Ni-In(2.0)/AA 773 K/H2
catalyst, and the results are summarized in Table 6.
The used Ni-In(2.0)/AA catalyst was easily separated by either
simple centrifugation or filtration after the reaction. The activity of
the catalyst slightly decreased, while a high selectivity was main-
tained for at least five consecutive runs. The amount of Ni and In that
leached into the reaction solution was 0.7% and 1.4%, respectively,
after four runs. The small amount of leached metal is consistent
3.2.6. Kinetics
The kinetics of F hydrogenation at 453 K on the bulk and
supported Ni-In(2.0)/AA 773 K/H2 alloy catalysts are shown in
Fig. 7. When the bulk Ni-In(2.0) catalyst was used, FA was slowly
with the XRD patterns of the recovered Ni-In(2.0)/AA 773 K/H cata-
2

5
8
Rodiansono et al. / Molecular Catalysis 445 (2018) 52–60
Fig. 3. Raman spectra of (a) the as-prepared Ni-In(2.0)/AlOH and (b) after H2 treat-
ment at 673 K for 1.5 h (Ni-In(2.0)/AA)).
Fig. 2. XRD patterns of the H2-treated Ni-In(x)/AA at a temperature of 673 K for 1.5 h
◦
and selected area at 2␪ = 40−50 for (a) 5.1, (b) 3.1, (c) 2.0, (d) 1.1, and (e) 0.8. (ꢀ)
Ni(0); (*) bimetallic Ni3In (#JCPDS-21-404).
lyst, and no obvious phase separation or agglomeration of the Ni In
2
nanoparticles was observed in the used Ni-In(2.0)/AA 773 K/H cat-
2
alyst, as indicated by the XRD patterns (Fig. S7 in the ESI).
Fig. 4. XRD patterns of (a) as-prepared Ni-In(2.0)/AlOH and H2 treated (Ni-
In(2.0)/AA) at different temperatures of (b) 573, (c) 673, (d) 773, and (e) 873 K for
4
. Conclusions
1
.5 h. (᭹) bayerite; (⊗) gibbsite; (#) In(OH)3; (ꢀ) Ni(0); (*) Ni3In (#JCPDS-21-404);
A novel preparation method for bimetallic nickel-indium alloy
(ꢁ) Ni In (#JCPDS-65-3486).
2
3
catalysts supported on amorphous alumina (Ni-In(x)/AA; x = Ni/In
molar ratio) catalysts has been developed and evaluated for the

Rodiansono et al. / Molecular Catalysis 445 (2018) 52–60
59
Fig. 7. Kinetics of the hydrogenation of furfural (F) over bimetallic bulk Ni-In(2.0)
and Ni-In(2.0)/AA catalysts. Reaction conditions: catalyst, 50 mg; F, 1.1 mmol; iso-
PrOH, 3 mL; H2, 3.0 MPa, 453 K.
Fig. 5. Effect of reaction temperature on the conversion of furfural (F) over the bulk
and supported Ni-In(2.0)/AA 773 K/H2 alloy catalysts. Reaction conditions: catalyst,
5
0 mg; F, 1.1 mmol; iso-PrOH, 3 mL; H2, 3.0 MPa, 75 min.
national Publication Project of DGHE FY 2016 under Grant Number
of DIPA-023-04.1.673453/2016, Insentif Riset Nasional (Insinas) FY
2
016-2017, and IPTEKS Project FY 2016, Ministry of Research, Tech-
nology & Higher Education, Republic of Indonesia.
Appendix A. Supplementary data
Supplementary data associated with this article can be found,
in the online version, at http://dx.doi.org/10.1016/j.mcat.2017.11.
0
04.
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